Generally, semiconductor devices include a plurality of circuits that form an integrated circuit (IC) fabricated on a semiconductor substrate. A complex network of signal paths is routed to connect the circuit elements distributed on the surface of the substrate.
To efficiently route these signals across the device, multilevel or multilayered schemes are used, for example, single or dual damascene wiring structures. The wiring structure may include, for example, copper or a copper alloy. Copper-based interconnects may provide higher speed signal transmission between large numbers of transistors on a complex semiconductor chip than other types of interconnects, for example, aluminum-based interconnects.
Interconnects must reliably transmit power from one portion of the circuit to another with a minimal loss of power due to resistance. This becomes increasingly difficult as the size of the interconnect decreases in response to overall decreases in feature size.